1. Field of the Invention
The invention relates to a valve, more particularly to a foot-operated valve for faucets and the like.
2. Description of the Related Art
Presently, the control of water flow through most faucets installed in public places, such as in hospitals and public toilets, is usually accomplished by rotating a handle or by applying pressure on a lever. Thus, the risk of being infected with a disease is relatively high because of the need to operate the faucet by hand. In order to overcome this drawback, some establishments have installed faucets which incorporate a sensor to control water flow. However, such faucets can only provide a predetermined amount of water when in use and is incapable of satisfying the water needs of different people.
One of the applicants of the present invention has disclosed in co-pending U.S. patent appln. Ser. No. 08/199,885, filed on Feb. 22, 1994, a foot-operated valve which is convenient to use, which can minimize the risk of infection because it obviates the need for operating the same by hand, and which can be used to provide varying amounts of water to satisfy the needs of different people. Although this foot-operated valve provides numerous advantages over the conventional water flow control devices commonly installed in faucets, it is somewhat inconvenient to use because pressure must be applied on the foot-operated valve continuously to obtain a continuous flow of water.
The applicants of this invention disclosed in copending U.S. patent appln. Ser. No. 08/271,518, filed on Jul. 7, 1994, a foot-operated valve which permits the continuous flow of water without the need for applying pressure continuously thereto. This foot-operated valve comprises a housing, a support plate, a valve set, a retaining plate unit, an extension spring means and a switch assembly.
The housing has an open top, a closed bottom and a surrounding wall formed with a first set of water outlet and inlet holes. One of the water outlet and inlet holes is disposed at a level higher than the other one of the water outlet and inlet holes. The support plate is mounted on the open top of the housing and is formed with a first hole.
The valve set includes a hollow seat, a tubular sleeve, a push rod, and a compression spring. The hollow seat is secured in the housing below the support plate and has an upright tube portion with an open top and a closed bottom. The tube portion confines an interior and is formed with radially extending outlet and inlet pipe connectors aligned with the first set of water inlet and outlet holes and communicated with the interior of the tube portion. The tubular sleeve is secured to and extends into the tube portion. The sleeve confines an axial through-hole and is formed with a passage means to communicate the through-hole and the outlet pipe connector. The push rod extends sealingly and slidably through the tubular sleeve and into the tube portion of the hollow seat. The push rod has a top end which extends out of the open top of the housing via the first hole of the support plate and a bottom end which has a plug secured therearound. The push rod is formed with an annular peripheral groove immediately above the plug and a radial first retaining unit adjacent the top end. The compression spring is provided in the upright tube portion and is interposed between the closed bottom of the tube portion and the push rod to bias the push rod upwardly so that the plug closes normally a distal bottom end of the tubular sleeve. When pressure is applied on the top end of the push rod against action of the compression spring, the plug moves away from the distal bottom end of the tubular sleeve so as to permit water entering the inlet pipe connector to reach the outlet pipe connector via the interior of the tube portion, the annular peripheral groove of the push rod, and the through-hole and the passage means of the tubular sleeve.
The retaining plate unit is disposed below the support plate and includes an elongated plate which is supported movably by the support plate and which is movable in a lateral direction towards and away from the push rod of the valve set. The elongated plate has a rear end and a front end formed with a second retaining unit. The extension spring means biases the second retaining unit of the elongated plate toward the push rod of the valve set to enable the second retaining unit to engage the first retaining unit on the push rod when pressure is applied on the top end of the push rod. The switch assembly includes a switch means operable selectively so as to pull the elongated plate against action of the extension spring means in order to disengage the second retaining unit from the first retaining unit, thereby permitting the compression spring to bias the push rod so that the plug closes the distal bottom end of the tubular sleeve.
Although a continuous flow of water can be obtained without applying pressure continuously on the above mentioned foot-operated valve, it is noted that the foot-operated valve is somewhat large and relatively complicated in construction.